In D. Wang et al, Acta Pharmaceutica Sinica, vol. 15, 253 (1980), flavone derivatives in which an alkylaminopropanoloxy side chain is inserted at either the 4', 5-, 6-, or 7-position of the flavone nucleus were disclosed.
In P. Da Re et al, Journal of Medicinal Chemistry, vol. 15, 868 (1972), flavone derivatives in which an alkylaminopropanoloxy side chain is inserted at either the 6- or 7-position of the flavone nucleus, and a methyl group is also inserted at the 3-position of the flavone nucleus, were disclosed.
U.S. Pat. No. 4,391,821 dated July 5, 1983, claimed various benzopyran derivatives in which an alkylaminopropanoloxy side chain is inserted at the 7-position of the benzopyran nucleus and disclosed that the derivatives were useful in treatment of heart disease.
The above-mentioned publications and patent did not disclose benzopyran derivatives with either ester derivatives of the propanoloxy side chain or a side chain substituted at the 8-position.